Knife sharpening mechanism



Aug. 14, 1951 F. G. CLARK 2,563,921

' KNIFE SHARPENING MECHANISMS Filed Sept. 5, 1950 5 Sheets-Sheet 1 IN VEN TOR.

Aug. 14, 1951 F. G. CLARK 63,

KNIFE SHARPENING MECHANISMS Filed Sept. 5, 1950 5 Sheets-Sheet 2 INVEN TOR. a? M Aug. 14, 1951 F. s. CLARK 2,563,921

KNIFE SHARPENING MECHANISMS Filed Sept. 5, 1950 5 Sheets-Sheet 4 75 60 6.9 11v an OR. 70 73 60 Y Offer 716:93'.

g- 14, 1951 F. e. CLARK 2,563,921

KNIFE SHARPENING MECHANISMS Filed Sept. 5, 1950 5 Sheets-Sheet 5 IN V EN TOR.

Patented Aug. 14, 1951 KNIFE SHARPENING MECHANISM Frederick G. Clark, Buffalo, N. Y., assignor to Eastman Machine Company, Bufialo, N. Y.

Application September 5, 1950, Serial No. 183,182

6 Claims.

1 This invention relates to knife sharpening mechanisms for cutting machines of the type commonly used for cutting cloth and other sheet materials, such as disclosed in my co-pending.

application No. 779,622, filed October 13, 1947, now Patent No. 2,537,208, dated January 9, 1951.

One of the objects of this invention is to provide a knife sharpening mechanism having means of improved construction for actuating the carriage on which the grinding means are mounted.

A further object is to provide improved presser foot locking mechanism for holding the presser foot of the cutting machine in such a manner that no damage will result to the grinding mechanism or the presser foot if the same is not lowered before starting the knife sharpening mechanism.

A further object is to provide a mechanism for releasably holding the presser foot against upward'movement from any lowered position in which it cooperates with the material which is being out, but which permits the same to be freely moved downwardly, for example, by the grinding carriage.

other objects and advantages will be apparent from the following description of some embodiments of the invention, and the novel features will be particularly pointed out hereinafter in connection with the a ended claims.

In the accompahyingdrawings.

Fig. 1 is a side elevation, partly broken away, of a cloth cutting machine equipped with automatic knife sharpening mechanism embodying this invention and showing the position of the parts when the sharpening mechanism is out of action and with the grinding means in their initial, uppermost position.

' Fig. 2 is a fragmentary sectional elevation on an enlarged scale on line 2-2, Fig. 1.

Fig. 3 is a transverse, sectional view thereof on line 33, Fig. 2.

Fig. 4 is a fragmentary front elevation of the machine as seen from the front thereof, partly in section, and on a still larger scale.

Fig. 5 is a fragmentary, sectional view thereof on line 55, Fig. 4.

Fig. 6 is a fragmentary front elevation thereof, similar to Fig. 4, showing the parts in different positions.

Figs. '7 and 8 are fragmentary, sectional views thereof, respectively on lines 1-! and 8-8,

Fig. 6.

Fig. 9 is a fragmentary elevation thereof taken generally along line 9-9, Fig. 10, showing the presser foot locking mechanism.

Fig. 10 is a fragmentary side elevation thereof.

Fig. 11 is a fragmentary sectional elevation thereof on line Ill I, Fig.

Fig. 12 is a fragmentary sectional view thereof on line l2l2,Fig. 11.

The cutting machine and its knife sharpening mechanism, except as hereinafter described, may be of known or other suitable construction. As herein disclosed, the machine comprises the usual base 20 adapted to rest and be moved about on the supporting table for the lay of material to be cut; an upright, slender standard 2| rigidly secured on and rising from the base and supporting the stationary frame or portion 22 of the electric motor which reciprocates the knife 23 in a vertical guide at the front of the standard through suitable drive mechanism including a crank or flywheel 24 on the front end of the horizontal rotor shaft of the motor, and which is suitably connected, for example, by means of a pitman and crosshead (not shown) to the upper end of the knife. The machine also includes a presser foot 26 on the lower end of a guard bar 21 which extends vertically in front of the knife and is suitably mounted for vertical adjustment on the machine to set the presser foot at different levels according to the thicknesses of different lays or piles of material.

In the machine as illustrated in the drawings, the knife is sharpened by grinding means of known type comprising two narrow abrasive belts or bands 30 and 3| which are disposed at opposite sides of the knife to travel crosswise of the knife in sharpening contact with opposite sides of the knife edge, around front drive pulleys 32 and 33 and rear, spring-actuated, belt-tensioning pulleys 34 and 35, the belts being power driven by the knife operating motor. The pulleys for the grinding belts are carried on the under side of a carriage 36 arranged to move or travel up and down lengthwise of the knife edge to enable the belts to sharpen the knife edge throughout its full length. The grinding belts or elements together with their driving mechanism and other parts of the sharpening mechanism may be mounted on a supporting housing or cover piece 38 which is stationarily but removably secured in place on the motor frame 22 at the front of the machine and serves to conceal the crank wheel 24 and other parts of the knife operating and sharpening mechanisms. The grinder carriage may be mounted and guided in its up and down movements and the grinding belt means constructed and mounted on the carriage in any suitable. or customary manner, for example, as more fully described in Patent #2,l83,'786, issued December 19, 1939, to Eastman Machine Company, assignee. While the sharpening mechanism of this invention preferably employs flexible belt grinding means, such as disclosed, the invention is not limited thereto and different grinding elements or means may be employed. v

The drive mechanism for the grinding belts or elements, as shown in the drawings, is con: structed as follows: The belt drive pulleys 32 and 33 are fixed on the lower ends of two vertical shafts 59 and M which rotate but are held from axial movement in suitable bearings on. carriage 36, so as to move up and down with the carriage. Said shafts extend up into the housing or cover piece 38 and are movableaxially through, but caused to rotate with intermeshing pinions 32 and 63, Figs. 2 and 3, which are held from axial movement in suitable bearings in the lower end of housing 38 and are oppositely rotated by a pinion i lon the lower end of a vertical shaft 45, rotatable in suitable hearings in the housing. A spiral gear train 45, ll, 58 operatively connects the. upper portion of. shaft 45 with the shaftof a wheel 49, which is adapted to be moved'into and out of contact with crank wheel 24 to be driven thereby. For this purpose, the shaft 50 of wheel 59 may be rotatably supported in a bearing inla bell crank lever i pivotedon a stud shown in broken lines in Figs. 2, 4 and 6, which is fixed in housing 38 and forms the axle for the idler spiral gear 41. A spring 53, Figs. 2 and l, acting between one arm of lever 5| and an opposing portion. of housing 38, tends to swing said lever about its pivot to press wheel 49 with a frictional tire or peripheral band: thereon into contact with the crank wheel 24, whereby when wheel 49 is pressed against the crank wheel 2 it is driven, and through the described gear trains,

shafts and pulleys, drives the grinding belts 30' and 3|.

The belt pulley shafts, 4D and M are preferably of square or non-circular shape in cross section and slidably engage in correspondingly shapedaxial holes in their driving pinions 42, 43, and each shaft is held in intended axial position from whipping or lateral motion by a cylindrical bushing 55, one of which is shown in Fig. 4. Each bushing is secured onthe upper. end of its shaft and is arranged to revolve and slide axially in a vertical. guide tube 56 suitably mounted stationarily in housing 38.. This arrangement provides much more durable connections between the pulley shafts and their driving pinions, and is more economical to produce than the usual splined arrangement of pinions on shafts, as by means of keys in the pinions slidably engaging in longitudinal keyways in the shafts.

An arm of lever 55 is pressed by spring 53 toward the upper end of a push rod 51 which is slidable vertically in suitable guide bearings E3 in housing 38 with its lower end projecting below the housing in position to be engaged by grinder carriage 35. When the grinder carriage is moved to its upper, initial position, it raises push rod 57 and shifts lever 5| against the action of the spring 53 to move and hold driven wheel 49 out of contact with crank wheel 24, thus stopping operation f the sharpening mechanism. When the sharpening mechanism is started to sharpen the knife, the grinder carriage is lowered, as later explained, and permits push rod 5'! to descend and allow driving engagement of wheel 49 with the crank wheel, as shown in Fig. 2.

The traversing mechanism for producing the up and down or to and fro travel of the grinder carriage 36 and grinding elements or belts along the knife edge is preferably constructed as follows: 60 represents a screw shaft, having crossing right and left hand screw threads. This screw shaft may be rotated in any suitable manner, and in the construction shown, the rotating means therefor are located in the grinder carriage 36. In this. construction the lower end of the screw shaft is journalled to rotate in the grinder carriage and held against axial movement relatively to the carriage by thrust collars 6| and Gla, Fig. 6. A part of the lower end of the screw shaft is of a square or non-circular 3 cross section to extend through a similarly shaped base. in a gear 62 which meshes with a pinion 83 secured onan idler shaft 64 on which a larger gear 65-is also secured. The larger gear meshes with a gear 66 mounted on the belt pulley shaft il. Consequently, as the shaft 4| is rotated through the mechanism described, the-screw shaft 653 is turned through the speed reducing gear train 62, 63, 65 and 66, when the sharpening mechanism is in operationrfor driving, the grinding belts,

The screw shaft 69 extends vertically up through the housing 38 and passes through two nuts 61 and 68, one of thesenuts having a left hand thread engaging the left, hand thread of a shaft, and the other nut having a right hand thread engaging the right hand thread of the shaft. These nuts are held from axial movement relatively to the screw shaft between suitable bearings in the housing member 38, and preferably an anti-friction bearing 69 extends about the screw shaft between the adjacent inner ends of the nuts. By holding one of the nuts 61 or 68 from rotation while leaving the other nut free to. rotate, the screw shaft rotating in the stationary nut is moved axially upwardly or downwardly. In the construction shown, when the lower nut El is held against rotation, the screw shaft moves downwardly, and when the nut 68 is held, the screw shaft is moved, axially upwardly.

When both nuts are left free to rotate, there is no endwise movement of the screw shaft,

Suitable mechanism is provided for holding and, freeing the nuts, and in the construction shown by way of example for this purpose, a latch member or element 10 is provided which is mounted to swing about a pivot 'H secured in a part of the housing 33. This latch is provided with a dog or detent I2 which, when the dog is swung into theposition shown in Fig. 4, will extend into the, pathof rotation of wings. 13 ex-. tending outwardly from the nut 61. Thelatch also has another dog or detent 14' which extends into position to engage wings or projections 15 on the nut 68 when the latch is swung into the position shown in Fig. 6. Obviously, when one dog or detent is in position to engage the-wings of one of the nuts, the other dog will be out of against the action of the spring '5'! by means of a link, 19 pivotedat 89 to-the latch Ill and having ahandle Bl at the upper portion thereof. The link 19 is guided. in its movement by means of a pin 82 secured to the housing 38 and extending through a guide slot 83. A latch holding member 84 is provided which is pivoted at 85 on a fixed part of the housing 33 and which has an arm 85 extending into position to engage a shoulder 8"! on the latch 70. Consequently, when the handle 8! is pushed downwardly, the link 19 will swing the latch iii into the position shown in Fig. 4, in which position the arm 86 will move into engagement with the shoulder 8i of the latch and hold the latch in position to hold the nut 5'! against rotation, thus effecting downward movement of the screw shaft and the grinder carriage connected thereto. To ensure the swinging of the holding member 86, a spring 89 is provided, one end of which seats against a part fixed to the housing 33 and the other end of which engages an arm (in of the holding member. The spring 89, in the particular construction shown by way of example, is in the form of a coil spring extending about the screw shaft 65.

In order to start the sharpening mechanism, the starting handle 85 is pushed downwardly, which causes the latch iii to swing from the position shown in Fig. 6 into the position shown in Fig. 4, for interrupting rotation of the lower nut 87. During this movement of the latch H3, there is a neutral position in which both of the dogs 72 and M are disengaged from both'of the nuts 51 and fi8, leaving both nuts free to rotate. This permits the spring 53 to actuate the bell crank lever 5i to force the driven wheel 49 into contact with the crank wheel 24 and, consequently, through the gearing described, the screw shaft 66 will be rotated. The spring 53 will be free to swing the bell crank lever 5! for the reason that the push rod 57 will no longer be held in its upper position by the carriage 36, and this spring also moves the push rod 5'5 down to start downward movement of the carriage 36. Further movement of the latch 79 from its neutral position into position to engage a wing 13 of the lower nut 81 and thereby stopping its rotation, will cause downward travel of the screw shaft and the grinder carriage 35. The latch ll] will be held in the position shown in Fig. 4 by means of the holding member E i, as described. The downward movement of the screw shaft will continue until the latch '19 is moved back from the position shown in Fig. 4 to that shown in Fig. 6.

The upper end of the screw shaft 68 is provided with a reversing member or sleeve 93 which is slidable in a guide tube 94 into which the screw shaft Bil extends. The reversing member or sleeve is preferably adjustably mounted on the upper end of the screw shaft in any suitable manner and, in the construction shown, the screw shaft is provided at its upper end with a threaded stud or extension 95 having a threaded engagement with the reversing member or sleeve 83, and a lock nut 95 is provided for securing the reversing sleeve in the desired position. As shown in Fig. 6, as the screw shaft moves into the lower portion of its stroke, the reversing member or sleeve 93 engages the spring pressed arm 99 of the holding member and thus causes the holding member to swing about its pivot 35, so that the arm 86 thereof will disengage the shoulder 87 of the latch ii When this happens, the spring ll will return the latch from the position shown in Fig. 4 to that shown in Fig. 6, thus disengagingthe lower nut 3i and holding the upper nut 58 against rotation. This will cause the screw shaft 60 to move upwardly, thus moving the grinder carriage 35 upwardly. The upward knife as most suitable for 7 different character.

movement of the grinder carriage is stopped when a portion of this carriage engages the push rod 51, which swings the bell crank lever 5| about its pivot 52 against the action of the spring 53, and thus moves the driven wheel 49 out of contact with the crank wheel 24, thus stopping the operation of the sharpening mechanism and holding the carriage 35 in its upper position. The push rod 51 will thus be held in engagement with the bell crank lever 5! and, consequently, the sharpening mechanism will be held in its upper and inoperative position until the handle BI is again actuated by the operator. In order to avoid the possibility of damage to the machine in the event that the operator holds the handle iii in its lower position when the mechanism is about to begin to raise the grinder carriage, a pin 88 is provided on the link 79, which pin is located in the path of movement of the holding member 84 as it swings out of position to engage the shoulder 81 of the latch 16. Consequently, the positive swinging of the holding member 84 by means of the reversing sleeve 93 will force the link 19 upwardly so that the latch 18 will disengage the wings of the lower nut 61. Preferably, the holding member 84 is provided with an arm 89 which extends outwardly in position to be actuated by the operator and by means of which the holding member may be moved out of engagement with the latch '15.

The reversing sleeve 93 is axially adjustable on screw shaft SB, as by screwing the same on the reduced, threaded upper end of the shaft and fixing it in adjusted position, as by a lock nut 56, so that by appropriate adjustment of this sleeve, or by using sleeves of different lengths on the screw shaft, the extent of downward travel of the grinding means may be increased or decreased, as may be necessary for grinding the full length of the edge of a knife of one or another length or which may have a reciprocating stroke of one or another length. It is usual in cutting machines of the type disclosed herein to change the length of stroke of the reciprocating cutting materials of Also such machines are made so that the machine may be provided with a standard of one or another length and with a knife of appropriate length, to better adapt the machine for cutting material piles or lays of different heights. By using a reversing sleeve such as described, of appropriate length, or by appropriately adjusting the sleeve axially to different positions on the screw shaft, very simple and efiicient means are provided for causing the return or upward travel of the grinding means when, in its downward travel, it has reached the lower end of the knife, regardless of the length of the knife or the length of the reciprocating strokes of the knife, Furthermore, the reversing sleeve being cylindrical and rotatable and movable axially in a guide tube 94, effectually holds the upper end of the screw shaft from whipping or lateral motion during the operation of the,

sharpening mechanism.

Since the presser foot 26 is necessarily located in the path of movement of the grinder carriage 56, it is necessary to provide means whereby damage to the machine is avoided in case the sharpening mechanism is actuated before the presser foot has been moved to its lowest position. In the construction illustrated, this is accomplished by providing a mounting for the presser foot by means of which the presser foot rod or guard bar 21 may be locked against upward movement by the goods which are being cut, but is free to move downwardly if engaged by the downwardly moving grinder carriage.

In the construction shown for this purpose, see Figs. 9-12, a cam member or arm I05 is provided, the outer end of which is shaped to cooperate with the presser foot rod 21 which, in the construction shown, is square in cross section. This cam member or arm I05 is pivoted on the frame of the machine and biased to move into an inclined position, as shown in Fig. 11, in which the arm extends downwardly at a slight inclination from its pivot to the rod 27. The outer end of the arm is notched or recessed to engage the foot rod 21'. It will be obvious that when the arm I05 is in the position shown in Fig. 11, upward movement of the rod 2'! is prevented while downwardly movement is not materially resisted by means of the arm I535. Consequently, when the presser foot is engaged by the downwardly moving grinder carriage, this carriage will move the presser foot and its guide rod 21 downwardly.

The arm I85, however, by a camming action prevents upward movement of the presser foot and its rod 21 by the goods which are being cut. In adjusting the presser foot into proper relation to such goods the same may be moved downwardly manually to the correct position. In order to effect upward movement, however, it is necessary to swing the arm Hi5 out of engage ment with the presser foot rod 21.

The mechanism for effecting these results may be constructed in any suitable or desired manner. In the construction illustrated by way of example, the arm I05 is formed by the end portions of two metal pieces or strips bent into approximately z shape, one end of each strip being secured to a corresponding end of the other strip to form the arm I65, the ends of the strips being bevelled to form a notch or recess which cooperates with two adjacent sides of the square presser foot rod shown by way of example in the drawings. The opposite ends of the two strips are spaced from each other and bent to extend substantially parallel to the arm I05 and are provided with suitable stub shafts or trunnions I07 and H38 rigidly secured thereto and journalled in suitable bearings in the frame member 38 of the machine. One of the strips is provided with an outwardly extending arm N39 to which one end of a coil spring H is attached, the other end of this spring being secured to the frame of the machine. This spring exerts pressure on the arm I09 to swing the other arm or cam member I into engagement with the presser foot rod. The spring H0 is preferably coiled about a bushing or sleeve, I II through which the shaft I08 extends.

The movement of the arm I05 out of engagement with the presser foot rod may be effected in any suitable or desired manner, and, in the construction shown, a bevel gear H4 is secured to the end of the shaft I98 and meshes with another bevel gear H5 secured on a rod or shaft H6 which forms a part of a crank handle III which extends outwardly from the machine into a position convenient to the operator. Consequently, when the operator swings the crank arm ID] in a clockwise direction in Fig. 9, the shafts Ill! and I08 will be turned to swing the arm I115 secured thereto in a clockwise direction in Fig. 11, out of engagement with the presser foot rod, so that the presser foot may be adjusted relatively to the material to be cut- If desired, another spring H8 may be provided which acts on the shaft IIG to cooperate with the spring H0 to return the handle to normal position, in which the presser foot rod is locked against upward movement. Any other means for actuating the arm or cam member I may be provided.

It will be understood that various changes in the details, materials and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended calms.

I claim as my invention:

1. In a knife sharpening mechanism for cutting machines having a knife, driven grinding means for the knife edge mounted on a movable supporting carriage movable to and fro along the knife edge by a rotatable and axially movable screw shaft having right and left hand threads, and a pair of nuts held from axial movement and operatively engaging respectively the right and left hand threads of said shaft, that improvement which includes a latch member pivotally mounted on the cutting machine and having a pair of detents mounted in spaced relation on said latch, said latch member when swung into one position moving one of said detents into position to hold one of said nuts against turning and releasing the other detent from the other nut, and when swung into another position releasing said first detent from said first nut and swinging said other detent into holding engagement with said other nut, said first nut when held against rotation causing said screw shaft to move said grinding means in one direction lengthwise of said knife and said other nut when held against rotation causing said screw shaft to return said grinding means to its initial position, said latchv member being movable manually in one direction to move said first detent to engage said first nut, a holding member for holding said latch in said last mentioned position, resilient means for urging said latch member to swing about its pivot into engagement with the other of said nuts when said holding member releases said latch, and

means actuated by the movement of said screw shaft in said first mentioned direction for releasing said holding member to permit said yielding means to swing said latch member into position, to reverse the movement of said screw shaft.

2. A knife sharpening mechanism according to claim 1, characterized in that said screw shaft has a part mounted thereon which engages said holding member to move the same into position to release said latch when said screw shaft has completed its downward motion.

3. A knife sharpening mechanism according to claim 1, and including a link connected with said latch and movable manually to swing said latch into position to effect downward movement of said screw shaft.

l. A knife sharpening mechanism according to claim 1, and including a link connected with said latch and movable manually to swing said latch into position to effect downward movement of said screw shaft, and a part on said link extending into a position to be engaged by said holding member when the same is moved into latch releasing position to positively move said link into position to permit said yielding means to move said latch member into position to engage said other nut for moving said screw shaft in a reverse direction.

5. In a knife sharpening mechanism for cutting machines having a knife, driven grinding means for sharpening the knife edge, a movable supporting carriage for the grinding means, a presser foot for the work and a presser foot rod adjustable on said machine to change the position of the presser foot relatively to the work, that improvement which includes an arm pivoted on the machine, yielding means for urging said arm into a position in which the outer end of said arm engages said presser foot rod while extending downwardly from said pivot into engagement with said rod to prevent upward movement of said rod and permitting downward movement of said rod when said presser foot is 10 engaged by said carriage, and means extending into a position accessible to the operator for swinging said arm into position to release said presser foot rod.

6. A knife sharpening mechanism according to claim 5 and including a shaft on which said arm is mounted, and means connected with said shaft for turning the same against the action of said yielding means for swinging said arm out of 10 engagement with said presser foot rod.

FREDERICK G. CLARK.

No references cited. 

